Color coating chromium-free pretreatment solution for galvanized plate

Abstract

The invention discloses a color coating chromium-free pretreatment solution for a galvanized plate, and belongs to the technical field of chromium-free passivation of galvanized plates. The color coating chromium-free pretreatment solution comprises the following components in percentage by mass: 8 to 20 percent of organic silane, 1.2 to 4 percent of inorganic salt, 1 to 2 percent of oxidant, 0.12 to 0.24 percent of complexing agent and the balance of deionized water serving as a solvent. The pH value of the chromium-free pretreatment solution is 3 to 4, and is regulated through inorganic acid. The chromium-free pretreatment solution can form a three-dimensional netlike compact organic silane blocking layer based on a formed inorganic metal compound precipitation membrane; and meanwhile, because the organic silane is added, the bonding force of a passivation film and a galvanized layer can be increased, the corrosion resistance, washing resistance and abrasion resistance of the passivation layer can be improved, and the requirement of a color coating process can be fully met. The pretreatment solution can be prepared by using the conventional passivation equipment and processes, does not contain chromium, and is environmentally-friendly passivation solution.

Description

Technical field: [0001] The invention belongs to the technical field of chromium-free passivation of galvanized sheets, and in particular relates to a chromium-free pretreatment solution for improving the corrosion resistance and coating performance of galvanized sheets. Background technique: [0002] Color-coated steel plate has light weight, beautiful appearance and good anti-corrosion performance, and can be processed directly. It provides a new type of raw material for the construction industry, shipbuilding industry, vehicle manufacturing industry, furniture, electrical and other industries, and plays a role in replacing wood with steel. , efficient construction, energy saving, pollution prevention and other good effects. The galvanized sheet used for color coating needs surface pretreatment and passivation to form a chemical passivation film on the surface of the steel sheet to improve the adhesion between the coating and the galvanized sheet and the corrosion resistan...

AI Technical Summary

Problems solved by technology

Chinese patent CN 1974842A discloses the use of passivation treatment solution compounded by organosilane and molybdate corrosion inhibitor, which can achieve the passivation effect of chromate under the same conditions, but in a more complex corrosion environment, such as neutral Salt spray test, its corrosion resistance effect needs to be improved

Chinese patent CN 101182640A discloses a layer of organic silane gamma-aminopropyltriethoxysilane coated on the surface of galvanized steel sheet, and then enters the compound salt of cerium salt and lanthanum salt after drying the steel sheet with hot air. It shows that although the white rust occurs 63 hours after the neutral salt spray test, and the adhesion of the test piece to the paint film is 0, the passivation process is relatively cumbersome, which increases the cost of the passivation process, so it is not suitable for promotion and industrial production.

[0005] Based on the above situation, although there are many studies on the chromium-free passivation of the zinc layer, and the proposed schemes are different, the corrosion resistance of the passivation film is far from that of the chromate passivation film.